On Jul 21, 2019, at 11:22 AM, Blaas Dieter wrote:

Hi Elaine,
thank you very much, but with a slice again colouring only works with "volume data gradient norm" see attached image. When changing to "volume data" I receive the message "no volume data for surface" and pushing "colour" does not change the appearance. Is there anything wrong with my mrc file?
bw Dieter

On 2019-07-21 18:15, Elaine Meng wrote:

Hi Dieter,
I don’t know specifically what’s happening in your case, but if you
are coloring an isosurface of the same volume data, by definition all
the values would be essentially the same.  Coloring by the volume data
value would normally be used on a slice of that isosurface, e.g. as
shown here:
<http://www.rbvi.ucsf.edu/chimera/data/tutorials/volumetour/volumetour.html#colorcap>
I hope this helps,
Elaine
-----
Elaine C. Meng, Ph.D.
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco

On Jul 21, 2019, at 5:36 AM, Dieter Blaas <dieter.blaas@meduniwien.ac.at> wrote:
Hi,
   Trying to color a volume according to "volume data" I get the same numerical values for all colors and a speckled appearance. When using "volume data gradient norm" I get the expected colors, i.e. strong local changes of the volume data are red and spots where there is essentially no change are in blue. How is this possible? If I understand correctly, "volume data gradient norm" colors according to the first derivative of "volume data" or is this wrong?  Do I need something like a normalization?
Thanks a lot for explanations,
best, Dieter

-- 
Dr. Dieter Blaas
Max F. Perutz Laboratories,
Inst. Med. Biochem.,
Med. Univ. Vienna
Dr. Bohr Gasse 9/3
A-1030 Vienna, Austria
Tel. 0043 1 4277 61630
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